In a prior art surface mounting light emitting diode, one end of the diode is a P type junction surface and another end thereof is an N type junction surface. The P type junction surface is connected to a positive electrode and the N type junction surface is connected to a negative electrode. The diode is operated by positive bias so that the surface mounting light emitting diode can light up. If the P type junction surface is connected to a negative electrode and the N type junction surface is connected to a negative electrode, then the diode is negative biased to that the diode will be in cut off mode and thus it can not light up.
Thus, in the prior art surface mounting light emitting diode, the diode must be connected by a predetermined direction. In application, it must be in positive bias state for application. If the connect is incorrect, the diode can not operate. The prior art surface mounted light emitting diode only support voltages of 3V to 5VF. If it is applied to a higher voltage, it must be externally connected to a lower voltage. If it is applied to a loop of high voltage, a shunt resistor must be externally connected thereto. As a result, not only the complexity in circuit design is increased, but also the cost is also increased.